Computers are pervasive in today's society. Large computer systems are often referred to as “mainframe” computers and have the capability of executing numerous tasks, often referred to as jobs, at the same time. Often customers of such a computer system desire certain jobs to be executed at certain times while other jobs may occur at times that are not predetermined. Thus, many computer systems use job schedulers to control when jobs are executed.
One example of such a scheduler is the Computer Associates Unicenter CA-7 Job Manager. In that system, a job manager accesses queue files regarding the status of certain jobs. In one example, the queue files include a request queue, a ready queue, an active queue, a prior run queue, and other miscellaneous queues. The request queue is a “look ahead” queue that includes prerequisites that must occur before a particular job may be executed. An example of a prerequisite is that another job must complete running before the next job is executed, or that a particular data set must be created before a job may be executed. The ready queue stores jobs that are ready for execution but that might have to wait to be executed due to some system requirement, such as waiting for the availability of a tape drive. The active queue stores jobs that are active, and the prior run queue stores jobs that have executed properly.
One problem with the above-described system is the time that is required to access the queue files. It is often time consuming to locate the files stored on disk, read the disks, and to transmit the read information back to the job manager.